Shoppers were evacuated Feb. 11 after some suffered symptoms consistent with being exposed to pepper spray or Mace, DeRuwe said. Reactions included coughing, watery eyes and noses, and scratchy throats.

No one suffered long term health damage, DeRuwe said.

Norman C. Brown, the FBI task force supervisor, said the incident "could be anything from a prank to an intentional act against a targeted store."